“Type A” men, if married, appear to be less at risk for diabetes and heart disease, according to a study by USC College psychologist Biing-Jiun Shen.

Previous studies have shown that angry, hostile or type-A personalities in men lead to increased blood sugar, a condition that can lead to type 2 diabetes and heart attacks.

However, marriage seems to reduce those risks among such men.

“Marriage seems to be a buffer, or a protective factor, against the negative effect of hostility, anger and type-A personality,” said Shen, who led the study. “Hostility and anger may be risk factors in increasing glucose levels only for unmarried older men.”

The findings were part of a nine-year study of 485 men with an average age of 59. When the research began, all the men had healthy glucose levels. Nine years later, the glucose levels in single men rose as expected.

High blood sugar is known to put people at higher risk for type 2 diabetes and coronary artery disease, the leading cause of death in the United States, said Shen, assistant professor of psychology in USC College.

Marriage appears to mitigate this risk, but the reasons why are unclear.

“Wives may either reduce stress levels for their spouses or it could be as simple as they help watch what goes into their husbands’ mouths,” Shen theorized. “A wife could be an emotional support to alleviate stress or assist in living a healthy lifestyle.”

The study found that depression appeared to have no relationship with blood sugar levels, an area Shen said is still being studied and debated.

Published in the July issue of Diabetes Care, the study was partially funded by the American Heart Association, the National Alliance for Research on Schizophrenia and Depression, the Department of Veteran Affairs and the Massachusetts Veterans Epidemiology Research and Information Center.